Not just yet! There are a couple of AUs that last left off with Oscar on his way to meet Bobby (and Rumsfeld, but Sam conveniently forgot to warn Oscar about the doggo before convincing him to go).
The Brothers Together AU, in which Sam and Dean met little Oscar when they were all kids.
Food and Monsters, an AU created by @neonthewrite and the origin of Oscar. I write a new installment of this series every year around contest time, so you can actually expect to see Oscar meet Bobby at last sometime in the next couple months!
From Burgers and Pixie Dust, the third in the Food and Monsters series:
“Oz, why didn’t you tell us you were by yourself?” Dean asked. His voice was softer than Oscar was used to. The familiar gruff cadence was so quiet it almost didn’t rumble at all. Oscar glanced up sheepishly and found Dean watching him with concern.
He shrugged helplessly. “I dunno,” he said. “It didn’t seem important, I guess…”
“You shouldn’t have to be alone,” Sam said, his own expression full of concern. Their solemn looks flustered Oscar more and more by the second.
“B-but I do,” he said, shrugging again. “What else am I s’posed to do?”
Sam and Dean shared a long look and Oscar wrung his hands. He never had picked up the knack for reading either of them. They were enigmatic, no matter how much trust he’d placed in them, and when they wanted to hide what they were thinking, they could.
“If you want,” Sam began, turning back to Oscar with a hopeful gleam in his eyes, “we could get you to a place where you don’t have to be by yourself. Somewhere we could visit you more often and everything, and you’d even have more access to food.”
“Someplace safe, Oz. You deserve it after all that time,” Dean added. One hand approached and nudged gently at his shoulder. Just a gentle touch, and the hand retreated.
Oscar glanced around, wondering if they were playing a joke of some kind. Leaving the only place he’d ever known to live somewhere else? He’d never had a thought like that. It had never been a possibility before. “Um. Where is it? Is it far?”
Brothers Apart 